GROUNDWATER
Groundwater is the word used to describe water that saturates the ground,
filling all the available spaces. By far the most abundant type of groundwater
is meteoric water; this is the groundwater that circulates as part of the water
cycle. Ordinary meteoric water is water that has soaked into the ground from
the surface, from precipitation (rain and snow) and from lakes and streams.
There it remains, sometimes for long periods, before emerging at the surface
again. At first thought it seems incredible that there can be enough space in
the “solid” ground underfoot to hold all this water.
The necessary space is there, however, in many forms. The commonest
spaces are those among the particles—sand grains and tiny pebbles—of loose,
unconsolidated sand and gravel. Beds of this material, out of sight beneath the
soil, are common. They are found wherever fast rivers carrying loads of coarse
sediment once flowed. For example, as the great ice sheets that covered North
America during the last ice age steadily melted away, huge volumes of water
flowed from them. The water was always laden with pebbles, gravel, and sand,
known as glacial outwash, that was deposited as the flow slowed down.
The same thing happens to this day, though on a smaller scale, wherever
a sediment-laden river or stream emerges from a mountain valley onto
relatively flat land, dropping its load as the current slows: the water usually
spreads out fanwise, depositing the sediment in the form of a smooth,
fan-shaped slope. Sediments are also dropped where a river slows on entering
a lake or the sea, the deposited sediments are on a lake floor or the seafloor at
first, but will be located inland at some future date, when the sea level falls or
the land rises; such beds are sometimes thousands of meters thick.
In lowland country almost any spot on the ground may overlie what was
once the bed of a river that has since become buried by soil; if they are now
below the water’s upper surface (the water table), the gravels and sands of the
former riverbed, and its sandbars, will be saturated with groundwater.
So much for unconsolidated sediments. Consolidated (or cemented)
sediments, too, contain millions of minute water-holding pores. This is
because the gaps among the original grains are often not totally plugged with
cementing chemicals; also, parts of the original grains may become dissolved
by percolating groundwater, either while consolidation is taking place or at
any time afterwards. The result is that sandstone, for example, can be as
porous as the loose sand from which it was formed.
Thus a proportion of the total volume of any sediment, loose or cemented,
consists of empty space. Most crystalline rocks are much more solid; a
common exception is basalt, a form of solidified volcanic lava, which is
sometimes full of tiny bubbles that make it very porous.
The proportion of empty space in a rock is known as its porosity. But note
that porosity is not the same as permeability, which measures the ease with
which water can flow through a material; this depends on the sizes of the
individual cavities and the crevices linking them.
Much of the water in a sample of water-saturated sediment or rock will
drain from it if the sample is put in a suitable dry place. But some will remain,
clinging to all solid surfaces. It is held there by the force of surface tension
without which water would drain instantly from any wet surface, leaving it
totally dry. The total volume of water in the saturated sample must therefore
be thought of as consisting of water that can, and water that cannot, drain
away.
The relative amount of these two kinds of water varies greatly from one
kind of rock or sediment to another, even though their porosities may be the
same. What happens depends on pore size. If the pores are large, the water in
them will exist as drops too heavy for surface tension to hold, and it will drain
away; but if the pores are small enough, the water in them will exist as thin
films, too light to overcome the force of surface tension holding them in place;
then the water will be firmly held.
段落大意：
1 地下水形成原因并探讨地下水储存方式探讨。
2.能够容纳大量地下水的最常见地方以及原因。
3.另一种小范围内形成准村地下水的突进：山间峡谷中河床中的沉淀物。
4.低洼地储存地下水。
5.除了松软的沉淀物，坚实的沉淀物也存在容纳地下水空隙。
6.结晶岩石中的特例：玄武岩。
7.多空性和渗透性之间的差异。
8.地下水也存在挥发现象。
9.决定地下水挥发的因素。
Paragraph 1: Groundwater is the word used to describe water that
saturates the ground, filling all the available spaces. By far the most abundant
type of groundwater is meteoric water; this is the groundwater that circulates
as part of the water cycle. Ordinary meteoric water is water that has soaked
into the ground from the surface, from precipitation (rain and snow) and from
lakes and streams. There it remains, sometimes for long periods, before
emerging at the surface again. At first thought it seems incredible that there
can be enough space in the “solid” ground underfoot to hold all this water.
1. Which of the following can be inferred from paragraph 1 about the
批注 [h1]: 判断此题为推断题。
ground that we walk on?
○It cannot hold rainwater for long periods of time.
○It prevents most groundwater from circulating.
○It has the capacity to store large amounts of water.
○It absorbs most of the water it contains from rivers.
本题定位在段尾句，At first thought it seems incredible…..推测出后续文章将
讲述为什么这个现象确是 credible。
批注 [h2]: 文中没涉及雨水的保留时
间长短问题。
批注 [h3]: 最后一句话也没说明水循
环系统问题
批注 [h4]: 文中也没有对此的推测。
2. The word “incredible” in the passage is closest in meaning to 词汇题
○Confusing 混乱的
○Comforting 安慰的
○Unbelievable 难以置信的
○Interesting 有趣的
Paragraph 2: The necessary space is there, however, in many forms. The
commonest spaces are those among the particles—sand grains and tiny
pebbles—of loose, unconsolidated sand and gravel. Beds of this material, out
of sight beneath the soil, are common. They are found wherever fast rivers
carrying loads of coarse sediment once flowed. For example, as the great ice
sheets that covered North America during the last ice age steadily melted away,
huge volumes of water flowed from them. The water was always laden with
pebbles, gravel, and sand, known as glacial outwash, that was deposited as the
flow slowed down.
3. The word “out of sight” in the passage is closest in meaning to
○Far away
○Hidden
○Partly visible
○Discovered
4. According to paragraph 2, where is groundwater usually found?
○Inside pieces of sand and gravel
○On top of beds of rock
○In fast rivers that are flowing beneath the soil
○In spaces between pieces of sediment
5. The phrase “glacial outwash” in the passage refers to
○Fast rivers
○Glaciers
○The huge volumes of water created by glacial melting
○The particles carried in water from melting glaciers.
Paragraph 3: The same thing happens to this day, though on a smaller
scale, wherever a sediment-laden river or stream emerges from a mountain
批注 [h5]: 对应第四题答案
批注 [h6]: 词汇题，视线看不见得地
方。B 选项！
批注 [h7]: 细节题，细节题定位一般
通过 n. adj. 或者 v.来定位的。本句话
首先是 groundwater, usually found.因
此定位在原文第二句话，The
commonest spaces are those …
批注 [h8]: 指代题，查找最靠近
glacial outwash 前面的名词：
pebbles ,gravel, and sand
valley onto relatively flat land, dropping its load as the current slows: the
water usually spreads out fanwise, depositing the sediment in the form of a
smooth, fan-shaped slope. Sediments are also dropped where a river slows on
entering a lake or the sea, the deposited sediments are on a lake floor or the
seafloor at first, but will be located inland at some future date, when the sea
level falls or the land rises; such beds are sometimes thousands of meters
thick.
6. All of the following are mentioned in paragraph 3 as places that
sediment-laden rivers can deposit their sediments EXCEPT
○A mountain valley
○Flat land
○A lake floor
○The seafloor
批注 [h9]: 对应第六题，先从山中峡
谷开始然后变成 flat land,而后是 lake
floor 或者是 seafloor. 因此 mountain
valley 始发地是不可能形成
sediment-laden
批注 [h10]: 此题为否定事实信息题。
定位到原文红字处！
Paragraph 4: In lowland country almost any spot on the ground may
overlie what was once the bed of a river that has since become buried by soil;
if they are now below the water’s upper surface (the water table), the gravels
and sands of the former riverbed, and its sandbars, will be saturated with
groundwater.
7. The word “overlie” in the passage is closest in meaning to
○Cover
○Change
○Separate
○Surround
Paragraph 5: So much for unconsolidated sediments. Consolidated (or
cemented) sediments, too, contain millions of minute water-holding pores.
This is because the gaps among the original grains are often not totally
plugged with cementing chemicals; also, parts of the original grains may
become dissolved by percolating groundwater, either while consolidation is
taking place or at any time afterwards. The result is that sandstone, for
example, can be as porous as the loose sand from which it was formed.
8. The phrase “so much for” in the passage is closest in meaning to
○That is enough about
○Now let us turn to
○Of greater concern are
○This is related to
9. The word “plugged” in the passage is closet in meaning to
○Washed
○Dragged
批注 [h11]: 覆盖
批注 [h12]: 到此为止，仅仅就这么多
的意思。
批注 [h13]: 可以通过上下文来判断。
批注 [h14]: 带入文中，明显不对，文
中是想说 Consolidated
批注 [h15]: 给予 unconsolidated
sediment 更多关注，但后面没有形成
比较的关系
批注 [h16]: 如果放在原文，那么后面
关于 consolidated sediment 会有类似
于 however,之类的承接词，要不然就
太突兀了！
批注 [h17]: 堵塞的
○Filled up
○Soaked through
Paragraph 6: Thus a proportion of the total volume of any sediment, loose
or cemented, consists of empty space. Most crystalline rocks are much more
solid; a common exception is basalt, a form of solidified volcanic lava, which is
sometimes full of tiny bubbles that make it very porous.
Paragraph 7: The proportion of empty space in a rock is known as its
porosity. But note that porosity is not the same as permeability, which
measures the ease with which water can flow through a material; this depends
on the sizes of the individual cavities and the crevices linking them.
10. According to paragraphs 6 and 7, why is basalt unlike most crystalline
forms of rock?
○It is unusually solid
○It often has high porosity.
○It has a low proportion of empty space.
○It is highly permeable.
11. What is the main purpose of paragraph 7?
○To explain why water can flow through rock
○To emphasize the large amount of empty space in all rock
○To point out that a rock cannot be both porous and permeable
○To distinguish between two related properties of rock
Paragraph 9: The relative amount of these two kinds of water varies
greatly from one kind of rock or sediment to another, even though their
porosities may be the same. What happens depends on pore size. If the pores
are large, the water in them will exist as drops too heavy for surface tension to
hold, and it will drain away; but if the pores are small enough, the water in
them will exist as thin films, too light to overcome the force of surface tension
holding them in place; then the water will be firmly held.
批注 [h18]: 细节题，对应第六段最后
一句话：make it very porous.
批注 [h19]: 推断题，此类型题要查找
but because 等这样词汇，而原文出现
but 表现出比较区分的意思，所以选
择D
批注 [h20]: 翻译：如果孔太大里面的
水将流出，因为水滴对于表面张力太
12. Which of the sentences below best expresses the essential information
in the highlighted sentence in the passage? Incorrect choices change the
meaning in important ways or leave out essential information.
○Surface tension is not strong enough to retain drops of water in rocks
with large pores but it strong enough to hold on to thin films of water in rocks
with small pores.
○Water in rocks is held in place by large pores and drains away from
small size pores through surface tension.
○Small pores and large pores both interact with surface tension to
determine whether a rock will hold water as heavy drops or as a thin film.
沉，表面张力无法承担。所以水分会
流失，但如果孔足够小，水在里面就
会变成一张薄的膜，因为太轻而无法
客服表面张力所以保留在里面，因此
水将牢牢保持住！
批注 [h21]: 只说到打孔没说到小孔！
批注 [h22]: 没有解释水分是怎么流
失的！
○If the force of surface tension is too weak to hold water in place as heavy
drops, the water will continue to be held firmly in place as a thin film when
large pores exist.
批注 [h23]: 洞大，洞小才决定表面张
力的大小，而不是直接张力大小决定
Paragraph 8: Much of the water in a sample of water-saturated sediment
or rock will drain from it if the sample is put in a suitable dry place.█ But
some will remain, clinging to all solid surfaces.█ It is held there by the force
of surface tension without which water would drain instantly from any wet
surface, leaving it totally dry.█ The total volume of water in the saturated
sample must therefore be thought of as consisting of water that can, and water
that cannot, drain away.█
水分流失，洞大洞小通表面张力没有
13. Look at the four squares [█] that indicate where the following
sentence could be added to the passage.
What, then, determines what proportion of the water stays and
what proportion drains away?
Where would the sentence best fit? Click on a square to add the sentence
to the passage.
批注 [h24]: 本题属于句子插入题，判
明确的表述！
断逻辑关系，方向如下：数字，代词，
某延续性动词
批注 [h25]: What proportion of the
water stays and what proportion drains
away ,正好对应上段红字部分！
14. Directions: An introductory sentence for a brief summary of the
passage is provided below. Complete the summary by selecting the THREE
answer choices that express the most important ideas in the passage. Some
sentences do not belong in the summary because they express ideas that are
not presented in the passage or are minor ideas in the passage. This question
is worth 2 points.
Much of the ground is actually saturated with water.
●
●
●
Answer choices
○Sediments that hold water were spread by glaciers and are still spread by
rivers and streams.
○Water is stored underground in beds of loose sand and gravel or in
cemented sediment.
○The size of a saturated rock’s pores determines how much water it will
retain when the rock is put in a dry place.
○Groundwater often remains underground for a long time before it
emerges again.
○Like sandstone, basalt is a crystalline rock that is very porous.
○Beds of unconsolidated sediments are typically located at inland sites
that were once underwater.
批注 [h26]: 文章内容小结题
批注 [h27]: 2,3 段介绍的内容
批注 [h28]: 2．3.4 段介绍的内容
批注 [h29]: 9 段介绍的内容
批注 [h30]: 没说
批注 [h31]: 信息错误，没说 basalt
like sandstone.而且，文中的 basalt 更
着重强调它通其他 crystalline rock
之间的区别，而不是同谁相似！
批注 [h32]: 以偏概全 inland 是指第
四段内容，但它不是 typically
参考答案
1. ○ 3
2. ○ 3
3. ○ 2
4. ○ 4
5. ○ 4
6. ○ 1
7. ○ 1
8. ○ 1
9. ○ 3
10. ○ 2
11. ○ 4
12. ○ 1
13. ○ 4
14. ○1 2 3